/*
 * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
 * Copyright (c) 2006 Christian Walter <wolti@sil.at>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * File: $Id: mb.c,v 1.27 2007/02/18 23:45:41 wolti Exp $
 */

/* ----------------------- System includes ----------------------------------*/
#include "stdlib.h"
#include "string.h"

/* ----------------------- Platform includes --------------------------------*/
#include "port.h"

/* ----------------------- Modbus includes ----------------------------------*/

#include "mb.h"
#include "mbconfig.h"
#include "mbframe.h"
#include "mbproto.h"
#include "mbfunc.h"

#include "mbport.h"
#if MB_SLAVE_RTU_ENABLED == 1
	#include "mbrtu.h"
#endif
#if MB_SLAVE_ASCII_ENABLED == 1
	#include "mbascii.h"
#endif
#if MB_SLAVE_TCP_ENABLED == 1
	#include "mbtcp.h"
#endif

#ifndef MB_PORT_HAS_CLOSE
	#define MB_PORT_HAS_CLOSE 0
#endif

/* ----------------------- Static variables ---------------------------------*/

static UCHAR    ucMBAddress;
static eMBMode  eMBCurrentMode;

static enum {
	STATE_ENABLED,
	STATE_DISABLED,
	STATE_NOT_INITIALIZED
} eMBState = STATE_NOT_INITIALIZED;

/* Functions pointer which are initialized in eMBInit( ). Depending on the
 * mode (RTU or ASCII) the are set to the correct implementations.
 * Using for Modbus Slave
 */
static peMBFrameSend peMBFrameSendCur;
static pvMBFrameStart pvMBFrameStartCur;
static pvMBFrameStop pvMBFrameStopCur;
static peMBFrameReceive peMBFrameReceiveCur;
static pvMBFrameClose pvMBFrameCloseCur;

/* Callback functions required by the porting layer. They are called when
 * an external event has happend which includes a timeout or the reception
 * or transmission of a character.
 * Using for Modbus Slave
 */
BOOL(*pxMBFrameCBByteReceived)(void);
BOOL(*pxMBFrameCBTransmitterEmpty)(void);
BOOL(*pxMBPortCBTimerExpired)(void);

BOOL(*pxMBFrameCBReceiveFSMCur)(void);
BOOL(*pxMBFrameCBTransmitFSMCur)(void);

/* An array of Modbus functions handlers which associates Modbus function
 * codes with implementing functions.
 */
static xMBFunctionHandler xFuncHandlers[MB_FUNC_HANDLERS_MAX] = {
#if MB_FUNC_OTHER_REP_SLAVEID_ENABLED > 0
	{MB_FUNC_OTHER_REPORT_SLAVEID, eMBFuncReportSlaveID},
#endif
#if MB_FUNC_READ_INPUT_ENABLED > 0
	{MB_FUNC_READ_INPUT_REGISTER, eMBFuncReadInputRegister},
#endif
#if MB_FUNC_READ_HOLDING_ENABLED > 0
	{MB_FUNC_READ_HOLDING_REGISTER, eMBFuncReadHoldingRegister},
#endif
#if MB_FUNC_WRITE_MULTIPLE_HOLDING_ENABLED > 0
	{MB_FUNC_WRITE_MULTIPLE_REGISTERS, eMBFuncWriteMultipleHoldingRegister},
#endif
#if MB_FUNC_WRITE_HOLDING_ENABLED > 0
	{MB_FUNC_WRITE_REGISTER, eMBFuncWriteHoldingRegister},
#endif
#if MB_FUNC_READWRITE_HOLDING_ENABLED > 0
	{MB_FUNC_READWRITE_MULTIPLE_REGISTERS, eMBFuncReadWriteMultipleHoldingRegister},
#endif
#if MB_FUNC_READ_COILS_ENABLED > 0
	{MB_FUNC_READ_COILS, eMBFuncReadCoils},
#endif
#if MB_FUNC_WRITE_COIL_ENABLED > 0
	{MB_FUNC_WRITE_SINGLE_COIL, eMBFuncWriteCoil},
#endif
#if MB_FUNC_WRITE_MULTIPLE_COILS_ENABLED > 0
	{MB_FUNC_WRITE_MULTIPLE_COILS, eMBFuncWriteMultipleCoils},
#endif
#if MB_FUNC_READ_DISCRETE_INPUTS_ENABLED > 0
	{MB_FUNC_READ_DISCRETE_INPUTS, eMBFuncReadDiscreteInputs},
#endif
};

/* ----------------------- Start implementation -----------------------------*/
eMBErrorCode
eMBInit(eMBMode eMode, UCHAR ucSlaveAddress, UCHAR ucPort, ULONG ulBaudRate, eMBParity eParity)
{
	eMBErrorCode    eStatus = MB_ENOERR;

	/* check preconditions */
	if((ucSlaveAddress == MB_ADDRESS_BROADCAST) ||
	        (ucSlaveAddress < MB_ADDRESS_MIN) || (ucSlaveAddress > MB_ADDRESS_MAX)) {
		eStatus = MB_EINVAL;
	} else {
		ucMBAddress = ucSlaveAddress;

		switch(eMode) {
#if MB_SLAVE_RTU_ENABLED > 0

			case MB_RTU:
				pvMBFrameStartCur = eMBRTUStart;
				pvMBFrameStopCur = eMBRTUStop;
				peMBFrameSendCur = eMBRTUSend;
				peMBFrameReceiveCur = eMBRTUReceive;
				pvMBFrameCloseCur = MB_PORT_HAS_CLOSE ? vMBPortClose : NULL;
				pxMBFrameCBByteReceived = xMBRTUReceiveFSM;
				pxMBFrameCBTransmitterEmpty = xMBRTUTransmitFSM;
				pxMBPortCBTimerExpired = xMBRTUTimerT35Expired;

				eStatus = eMBRTUInit(ucMBAddress, ucPort, ulBaudRate, eParity);
				break;
#endif
#if MB_SLAVE_ASCII_ENABLED > 0

			case MB_ASCII:
				pvMBFrameStartCur = eMBASCIIStart;
				pvMBFrameStopCur = eMBASCIIStop;
				peMBFrameSendCur = eMBASCIISend;
				peMBFrameReceiveCur = eMBASCIIReceive;
				pvMBFrameCloseCur = MB_PORT_HAS_CLOSE ? vMBPortClose : NULL;
				pxMBFrameCBByteReceived = xMBASCIIReceiveFSM;
				pxMBFrameCBTransmitterEmpty = xMBASCIITransmitFSM;
				pxMBPortCBTimerExpired = xMBASCIITimerT1SExpired;

				eStatus = eMBASCIIInit(ucMBAddress, ucPort, ulBaudRate, eParity);
				break;
#endif

			default:
				eStatus = MB_EINVAL;
				break;
		}

		if(eStatus == MB_ENOERR) {
			if(!xMBPortEventInit()) {
				/* port dependent event module initalization failed. */
				eStatus = MB_EPORTERR;
			} else {
				eMBCurrentMode = eMode;
				eMBState = STATE_DISABLED;
			}
		}
	}

	return eStatus;
}

#if MB_SLAVE_TCP_ENABLED > 0
eMBErrorCode
eMBTCPInit(USHORT ucTCPPort)
{
	eMBErrorCode    eStatus = MB_ENOERR;

	if((eStatus = eMBTCPDoInit(ucTCPPort)) != MB_ENOERR) {
		eMBState = STATE_DISABLED;
	} else if(!xMBPortEventInit()) {
		/* Port dependent event module initalization failed. */
		eStatus = MB_EPORTERR;
	} else {
		pvMBFrameStartCur = eMBTCPStart;
		pvMBFrameStopCur = eMBTCPStop;
		peMBFrameReceiveCur = eMBTCPReceive;
		peMBFrameSendCur = eMBTCPSend;
		pvMBFrameCloseCur = MB_PORT_HAS_CLOSE ? vMBTCPPortClose : NULL;
		ucMBAddress = MB_TCP_PSEUDO_ADDRESS;
		eMBCurrentMode = MB_TCP;
		eMBState = STATE_DISABLED;
	}

	return eStatus;
}
#endif

eMBErrorCode
eMBRegisterCB(UCHAR ucFunctionCode, pxMBFunctionHandler pxHandler)
{
	int             i;
	eMBErrorCode    eStatus;

	if((0 < ucFunctionCode) && (ucFunctionCode <= 127)) {
		ENTER_CRITICAL_SECTION();

		if(pxHandler != NULL) {
			for(i = 0; i < MB_FUNC_HANDLERS_MAX; i++) {
				if((xFuncHandlers[i].pxHandler == NULL) ||
				        (xFuncHandlers[i].pxHandler == pxHandler)) {
					xFuncHandlers[i].ucFunctionCode = ucFunctionCode;
					xFuncHandlers[i].pxHandler = pxHandler;
					break;
				}
			}

			eStatus = (i != MB_FUNC_HANDLERS_MAX) ? MB_ENOERR : MB_ENORES;
		} else {
			for(i = 0; i < MB_FUNC_HANDLERS_MAX; i++) {
				if(xFuncHandlers[i].ucFunctionCode == ucFunctionCode) {
					xFuncHandlers[i].ucFunctionCode = 0;
					xFuncHandlers[i].pxHandler = NULL;
					break;
				}
			}

			/* Remove can't fail. */
			eStatus = MB_ENOERR;
		}

		EXIT_CRITICAL_SECTION();
	} else {
		eStatus = MB_EINVAL;
	}

	return eStatus;
}


eMBErrorCode
eMBClose(void)
{
	eMBErrorCode    eStatus = MB_ENOERR;

	if(eMBState == STATE_DISABLED) {
		if(pvMBFrameCloseCur != NULL) {
			pvMBFrameCloseCur();
		}
	} else {
		eStatus = MB_EILLSTATE;
	}

	return eStatus;
}


eMBErrorCode
eMBEnable(void)
{
	eMBErrorCode    eStatus = MB_ENOERR;

	if(eMBState == STATE_DISABLED) {
		/* Activate the protocol stack. */
		pvMBFrameStartCur();
		eMBState = STATE_ENABLED;
	} else {
		eStatus = MB_EILLSTATE;
	}

	return eStatus;
}

eMBErrorCode
eMBDisable(void)
{
	eMBErrorCode    eStatus;

	if(eMBState == STATE_ENABLED) {
		pvMBFrameStopCur();
		eMBState = STATE_DISABLED;
		eStatus = MB_ENOERR;
	} else if(eMBState == STATE_DISABLED) {
		eStatus = MB_ENOERR;
	} else {
		eStatus = MB_EILLSTATE;
	}

	return eStatus;
}

eMBErrorCode eMBPoll(void)
{
	static UCHAR*   ucMBFrame;
	static UCHAR    ucRcvAddress;
	static UCHAR    ucFunctionCode;
	static USHORT   usLength;
	static eMBException eException;

	int             i;
	eMBErrorCode    eStatus = MB_ENOERR;
	eMBEventType    eEvent;

	/* Check if the protocol stack is ready. */
	if(eMBState != STATE_ENABLED) {
		return MB_EILLSTATE;
	}

	/* Check if there is a event available. If not return control to caller.
	 * Otherwise we will handle the event. */
	if(xMBPortEventGet(&eEvent) == TRUE) {
		switch(eEvent) {
			case EV_READY:
				break;

			case EV_FRAME_RECEIVED:
				eStatus = peMBFrameReceiveCur(&ucRcvAddress, &ucMBFrame, &usLength);

				if(eStatus == MB_ENOERR) {
					/* Check if the frame is for us. If not ignore the frame. */
					if((ucRcvAddress == ucMBAddress) || (ucRcvAddress == MB_ADDRESS_BROADCAST)) {
						(void)xMBPortEventPost(EV_EXECUTE);
					}
				}

				break;

			case EV_EXECUTE:
				ucFunctionCode = ucMBFrame[MB_PDU_FUNC_OFF];
				eException = MB_EX_ILLEGAL_FUNCTION;

				for(i = 0; i < MB_FUNC_HANDLERS_MAX; i++) {
					/* No more function handlers registered. Abort. */
					if(xFuncHandlers[i].ucFunctionCode == 0) {
						break;
					} else if(xFuncHandlers[i].ucFunctionCode == ucFunctionCode) {
						eException = xFuncHandlers[i].pxHandler(ucMBFrame, &usLength);
						break;
					}
				}

				/* If the request was not sent to the broadcast address we
				 * return a reply. */
				if(ucRcvAddress != MB_ADDRESS_BROADCAST) {
					if(eException != MB_EX_NONE) {
						/* An exception occured. Build an error frame. */
						usLength = 0;
						ucMBFrame[usLength++] = (UCHAR)(ucFunctionCode | MB_FUNC_ERROR);
						ucMBFrame[usLength++] = eException;
					}

					eStatus = peMBFrameSendCur(ucMBAddress, ucMBFrame, usLength);
				}

				break;

			case EV_FRAME_SENT:
				break;
		}
	}

	return MB_ENOERR;
}
